UPSC CAPF (AC) 2026 Paper I · Question 115

Question 115 of the UPSC CAPF (AC) 2026 Paper I (19 July 2026). Try it first, then open the answer and explanation.

1. CAPF 2026 · P-I · Q115 · General Science · Physics

   A uniform current-carrying narrow solenoid produces

   1. uniform magnetic field inside the solenoid
   2. uniform magnetic field outside the solenoid
   3. magnetic field with straight field lines in all the regions
   4. magnetic field with oscillating nature

   एकसमान विद्युत्-धारा वहन करने वाली संकीर्ण परिनालिका (solenoid) किसका उत्पादन करती है?

   1. परिनालिका के भीतर एकसमान चुम्बकीय क्षेत्र
   2. परिनालिका के बाहर एकसमान चुम्बकीय क्षेत्र
   3. सभी क्षेत्रों में सीधी क्षेत्र रेखाओं वाले चुम्बकीय क्षेत्र
   4. दोलायमान प्रकृति वाले चुम्बकीय क्षेत्र
   Show answer

   Answer: (1) uniform magnetic field inside the solenoid

   उत्तर: (1) परिनालिका के भीतर एकसमान चुम्बकीय क्षेत्र

   Inside a long, narrow solenoid carrying a steady current the field lines are straight, parallel and evenly spaced, so the field is uniform throughout the inside (B = μ₀nI). Outside, the field is very weak (nearly zero) and its lines curve round, so the other options are wrong.

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